Grade 11 Physical Sciences · Chemical Change

Define acid and base terms

Give the exact meaning of acid-base words like Lowry-Brønsted acid, strong acid, ampholyte and equivalence point.

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Question 7.1 · May/June 2025 · Paper 2 · National (DBE) · 2 marks

7.1 Define an acid according to the Arrhenius theory.(2)

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3. Question 7.2.1 · May/June 2024 · Paper 2 · National (DBE) · 2 marks
7.2 When $0, 01$ moles of dilute sulphuric acid, $H_{2} SO_{4}$ (aq), is mixed with $0, 024$ moles of potassium hydroxide, KOH(aq), the total volume of the final solution is $0, 2$ dm $^{3}$ .

$2 KOH(aq) + H_{2} SO_{4} (aq) \to K_{2} SO_{4} (aq) + 2 H_{2} O (ℓ)$

Answer the questions that follow.
7.2.1 What is meant by a dilute acid?(2)
Show the memo (1 tick)Memo
1. ✓
  Meaning of dilute acidDilute acid contains a small amount/number of moles of acid in proportion to the volume of water.
  2 marks · Define acid and base terms
4. Question 7.1 · November 2023 · Paper 2 · National (DBE) · 2 marks
To identify metal M in an unknown metal carbonate, $MCO_{3}$ , the following procedure is carried out:

Step 1: $0, 198$ g of IMPURE $MCO_{3}$ is reacted with $25$ cm $^{3}$ of $0, 4$ mol·dm $^{- 3}$ nitric acid, $HNO_{3}$ (aq).

Step 2: The EXCESS $HNO_{3}$ (aq) is then neutralised with $20$ cm $^{3}$ of $0, 15$ mol·dm $^{- 3}$ barium hydroxide, $Ba(OH)_{2}$ (aq).

Assume that the volumes are additive.

The following reactions take place:

$2 HNO_{3} (aq) + MCO_{3} (s) \to M(NO_{3})_{2} (aq) + CO_{2} (g) + H_{2} O (ℓ)$

$2 HNO_{3} (aq) + Ba(OH)_{2} (aq) \to Ba(NO_{3})_{2} (aq) + 2 H_{2} O (ℓ)$
7.1 Define the term strong base.(2)
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1. ✓
  Dissociates completelyA strong base (ionises) dissociates completely
  1 mark · Define acid and base terms
2. ✓
  In water to form a high concentration of OH⁻ ionsin water to form a high concentration of $OH^{-}$ ions.
  1 mark · Define acid and base terms
5. Question 7.1.1 · May/June 2022 · Paper 2 · National (DBE) · 2 marks
7.1 Two acids, HX and HY, of EQUAL CONCENTRATIONS are compared.

The pH of HX is $2, 7$ and the pH of HY is $0, 7$ .

Answer the questions that follow.
7.1.1 Define an acid in terms of the Lowry-Brønsted theory.(2)
Show the memo (1 tick)Memo
1. ✓
  Lowry-Brønsted acidAn acid is a proton ( $H^{+}$ ion) donor.
  2 marks · Define acid and base terms
6. Question 7.1.1 · November 2022 · Paper 2 · National (DBE) · 2 marks
7.1 Ethanoic acid is a weak acid that reacts with water according to the following balanced equation:

$CH_{3} COOH(aq) + H_{2} O (ℓ) ⇌ CH_{3} COO^{-} (aq) + H_{3} O^{+} (aq)$
7.1.1 Define an acid in terms of the Lowry-Brønsted theory.(2)
Show the memo (1 tick)Memo
1. ✓
  Lowry-Brønsted acid(An acid is a) proton donor / $H^{+}$ (ion) donor.
  2 marks · Define acid and base terms

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